The present invention relates to a controller for industrial robots and more particularly to a machine controller which is applicable when a control object (a mechanism comprising a robot(s) and one or a plurality of external axes) is commonly used for performing a plurality of jobs.
As disclosed in Japanese Unexamined Patent Publication No. Hei 4-252304, a known method exists for controlling a robot and a turntable comprising a plurality of axes and, as disclosed in Japanese Unexamined Patent Publication No. Sho 63-216689, it also causes a cooperative operation to be performed by a single robot and a plurality of positioners.
Further, as shown in FIG. 1, there exists a method by which three control objects (two robots (B) and (C) and a single station (A) comprising a plurality of axes) are controlled by a single controller. In this case, all the control objects (A) - (B) - (C) are controlled synchronously with one another or in such a manner that a cooperative operation is first performed between (A) and (B) and after that, a cooperative operation is performed between (A) and (C).
However, where all the control objects (A) - (B) - (C) are synchronously controlled, since the control objects are controlled in a simultaneous start/stop mode, they can not be controlled individually at separate speeds. Further, where a cooperative operation is performed between (A) and (C) after the completion of a cooperative operation between (A) and (B), the control object (C) can work independently during the cooperative operation between (A) and (B) and the control object (B) can work independently during the cooperative operation between (A) and (C). However, a problem exists in that control objects (C) or (B) cannot both perform a cooperative operation with (A) at the same time, thus lowering working efficiency.